""Assange remains in Belmarsh prison in London as he fights a US attempt to extradite him to face charges in connection with the publication of hundreds of thousands of leaked documents about the Afghanistan and Iraq wars as well as diplomatic cables."" That is the excuse for locking him up as that is what a reporters job is to report the news they're informed on.
Reporting this is in my opinion why they locked him up:
wikileaks:
07/31/2015
With fingers crossed, the old rabbit's foot out of the box in the attic, I will be sacrificing a chicken in the backyard to Moloch . . .
Tri (Name Hillary gave her self for these Emails found on wikileaks.)
https://archive.ph/7CFBA#selection-1189.84-1193.0 That one post took many of us on the deepest rabbit hole I never wanted to know about.